This patent document relates to oscillators based on optical and photonic devices for various applications, such as optical, radio frequency (RF), and microwave applications.
Optical devices may be used to manipulate or control light for applications where signals are not in the optical frequencies. As an example, RF and microwave oscillators for generating signals in the RF and microwave frequencies may be constructed as “hybrid” devices by using both electronic and optical components to form opto-electronic oscillators (“OEOs”). See, e.g., U.S. Pat. Nos. 5,723,856; 5,777,778; 5,929,430 and 6,567,436. Such an OEO includes an electrically controllable optical modulator and at least one active opto-electronic feedback loop that includes an optical part and an electrical part interconnected by a photodetector. The optical part of the opto-electronic feedback loop receives the modulated optical output from the optical modulator and the photodetector converts the light in the optical part into an electrical signal in the electrical part which is then used to produce a modulation control signal that controls the optical modulator. The feedback loop produces a desired long delay, e.g., in the optical part of the loop, to suppress phase noise and feeds the converted electrical signal in phase to the optical modulator to generate and sustain both optical modulation and electrical oscillation in RF or microwave frequencies when the total loop gain of the active opto-electronic loop exceeds the total loss. The generated oscillating signals are tunable in frequency and can have narrow spectral linewidths and low phase noise in comparison with the signals produced by other RF and microwaves oscillators.